This in vitro diagnostic quantitative reagent kit uses a competitive chemiluminescent immunoassay (CLIA) to measure free thyroxine (Free T4) in human serum or plasma. It requires 30 µL of specimen and features a 30-minute assay time. The analytical limit of quantification (LoQ) is 3.00 pmol/L. Precision is high: repeatability, reproducibility, and variation across locations/operators/batches all show CV <10%. The reagent is stored at 2-8°C, protected from light and not frozen. Certified under Taiwan FDA. Ideal for clinical thyroid function assessment and supportive diagnosis.